Artificial-lighting means.



E. J. BRADY.. ARTIFIGIAL LIGHTING MEANS.

APPLIGATION FILED 00T. 22, 1913.

Patented Dec.22,1914

Fl G. l.

/NVEWM Mme/vm DWARDJ. BRADY, or' PHILADELPHIA, PENNSYLVANIA,

AssrGNon r.ro THE UNITED GAS IMPROVEMENT COMPANY, OF PHILADELPHIA, PENNSYLVANIA, CORPORA- TIN OF PENNSYLVANIA..

ARTIFICIAL-LIGHTING. MEANS.

` Specification of Letters Patent.

Patented Dec. 22, 1914.

v Application filed ct'ober 22, 1913. Serial No. 796,552.

To all whom, it. may concern:

lBe it known thatL-EDWARD J. BRADY, a

` citizen of the United States, anda resident of Philadelphia, in the county of Philadelphia and. State of Pennsylvania, have invented certain new and useful Improve-- ments in Artificial-Lighting Means, of which thefollowing is a specification.

The invention relates to color filters or absorbing screens which operate to modify artificial light passing'through them so as to produce a resultant illuminationequiva- The principal` object of the present invention isv to provide an efiicient color filter or absorbing screen which may be constructed wholly of glass and which may therefore assume various forms useful in the arts, such as bulbs for incandescent electric lights and shades of various kinds.

.- The invention will vbe claimed at the end i hereof, but will befirst described in connection with the accompanying drawings, in which l Figure l, is a transverse sectional View of a color filter or absorbing screen embodying ,features of the inrention1 Fig. 2, is a similar viewillustrating a. modification thereof, and Fig. 8, is. a .diagrammatic view hereinafter referred to for the' sake of description.

Referring to the drawings and more particularly to Fig. 3, the rectangle 1 diagrammaticallv represents the spectrum of davlight; the letters V, I, B, G, Y, O and R, indicate the colors of that spectrum. The height of the rectangle represents the intensity of the Various colors `as present in the spectrum of daylight. The curved line 2 indicates the relative intensity of the va' rious colors in the spectrum of the artificial light which it is desired to Jmodify.

For the sake of illustration and explanation the spectrum of the artificial light source and the spectrum of the daylight source are drawn'as of equal intensities at the f extreme Violet. end. Artificial light sources as. generically represented by the area included under the curve 2 are usually Ididerent from daylight in possessing an excess of the longer spectrum Wave lengths, that is yellow, orange and red. An absorbing screen or color filter in order to alter an `artificial light spectrum to that of daylight must absorb these excessive radiations'. If the relative intensities of the different colors of the spectrum are plotted upon such a scale that the intensities of daylight and the artificial light sources are the same at the blue extremity of the spectrum, then the transmission of the absorbing screen must be as the reciprocal ofthe ratio at each color of the intensity of the artificial light spectrum to the daylight spectrum.

The color filter .or absorbing screen is adapted by absorptlon to produce the above described result, or perhaps more accurately,A

a very close approximation to it. In Fim 3,- the approximation is indicated by the dotted liiie 3 and dotted lines i, 5, 6, and T, indicate the absorptions diagrammaticallv and separately. line frein. the artificial light, reducing it from the curve 2 to the line 7. Similarly the dotted lines l, 5, and 6 represent other absorption's supplementary indicated by the line 7. VThe dotted line 3 indicates thenet result of the various absorptions as has been stated.

In the present invention the color filter or absorbing screen is of signal green andpurple color, with or without a blue color. There is nothing new about the signal green and purple color, but the point of the present .invention is that the color filter or screen may consist of glass containing or embodying these colors and since it is of glass, is otherwise proper and effective for the purpose in hand, it can be'used, for exam- For example, the dotted Indicates that red rays are absorbed-l to the absorptions ple, as the globe or bulb of an electric light"`= l and in that case there is provided a source of artificial illumination which has the effect of daylight, and such a. source of artificial v ,y

daylight illumination is so far as I know at present unknown.

I ani, ofcourse, aware of the color screens or filters have been made or suggested but I do not believe that there ever existed a source of -light such as an electric lamp in which the globe or bulb operated to make the electric lamp produce immediately and' directly the effect of daylightl illumination.

To produceglass of the requisite lpurple color, use is made of nickel which may be introduced as nickel oxid, or salts and the use of this material for the purpose of makfact that The absorbing function of the purple glass is diagrammaticaliyillustrated in Fig.

3 by the line 5. By purple color is meant that color or colors which absorb the intermediatecolors of the visible spectrum. The signal green absorbs the deep red rays from the artificial source, as is illustrated .dia- 'grammatically by the line in Fig. 3.

`lime glass is used the following `proportions produce good results:

.- Sand .208 pounds.

Potassiumcarbonate .091 Calcium carbonate-- .025 y Potassium nitrate--- .0167

To a batch weighing one-third of a pound 3o or 2,333 grains, Iour grains of black. nickel oxid, NizUs, may be added to produce the required kind of purple glass. '10 a similar batch l5 Vgrains oi' black copper -oxid may beadded to produce the signal green glass 3 5 of 'required color. When this is done the glasses would be'separate and could be intimately mixed. Instead of doing this the nickel oxid and the copper oxid in the quani tity stated may be added to the batchv of 40 glass and in that case the result is the same and. there is but one layer of glass. Oxid of cobalt may be added toa proper batch of glass, making material to produce blue glass, or the oxid of cobalt may be added along with vthe oxidof nickel and oxid of copper.

Byv way of .further description,v and not limitation, it may be said that Where potashl In giving proportions of the coloring'materials it must be borne in mind that the proportions are not hard Vand fast, but are to be changed so as to4 producethe desired result from any artificial light under consideration, having regard to the thickness of the glass. This is well understood by those skilled in the art.

It will be obvious to those skilled in the art that modifications may* be made in details without departing from the spirit of the invention, hence the same is not limitezdv require.

What I claim is: 1. A color filter or absorbin transforming the light of arti cial illuminants to daylight character comprisin'g a glass composition containing-nickel, copper and cobalt and being of generally blue co or further than the prior state ofthe art may when viewed by daylight.

A colorfilter or absorbing screen for transforming the light of .arti cial illumi- .nants to daylight character 'comprising a potash glass composition containing nickel,

copper and cobalt and being of generallyblue color when viewed by daylight. y

-A color filter or absorbinvr screen for transforming the light of varaaai illuminants to daylight character comprising. a

glass composition `containing nickel and copper and being of when viewed by daylight.-

4. A color lter or absorbin screen for transforming the light of arti cial illuminants to daylight character comprising a potash glass composition containing mckel and copper and being of generally blue color when viewed by daylight.

In Vtestimony whereof I have hereunto signed my name.

EDWARD J. BRADY.

W'itnesses: i CLIFFORD K. Cassel., FRANK E. FRENCH.

screen forl generally blue color 

